In recent years, as pixel miniaturization has progressed, a back-side illumination type solid-state imaging device intended to increase the numerical aperture has been proposed. In the back-side illumination type solid-state imaging device, an interconnection layer is positioned on the side opposite to the light illumination surface side, so there is no need to take into consideration light reflection by the interconnection, etc. This provides a given level of freedom to design of the interconnection layer. Hence, a photogate structure mainly intended to form a pseudo conductive diffusion layer by arranging a gate interconnection on each photodiode and applying a bias to its gate has been proposed. In the above-mentioned photogate structure, an n-type impurity, for example, is implanted into a region in, for example, a semiconductor substrate, where each photodiode is to be formed, thereby forming an n-type semiconductor layer.